This invention relates to an arrangement for identifying telephone stations served by telephone switching systems. Telephone switching centers of the telephone direct distance dialing network are equipped with switching systems each arranged to define a plurality of telephone offices serving particular ones of the telephone stations of the switching system. For example, a telephone switching center may comprise a number of switching systems, such as step-by-step and crossbar, each arranged to define telephone offices identified by a telephone office code and arranged to serve particular telephone stations. The telephone switching centers employ automatic message accounting equipment to automatically identify directory numbers assigned calling telephone stations in order that a telephone customer may be properly billed for use of telephone service.
Prior art automatic message accounting equipment provided for use in telephone switching centers initiates a request to identify a calling telephone station by applying a signal to trunk and junctor circuits which in turn conduct the signal to the calling telephone line circuit. A sleeve lead at the line circuit is connected from a main distributing frame to a station identifier matrix common to all telephone stations served by one telephone office of the telephone switching system. The telephone office station identifier matrix responds to the signal appearing on a sleeve lead by generating signals on ones of a plurality of digit leads identifying the directory number digits assigned the calling telephone station.
The telephone office station identifier matrix, being common to all telephone stations of a telephone office, is arranged to respond to an identification request signal by providing one telephone directory number identification at a time. In a telephone switching center equipped with a switching system having a plurality of telephone offices the prior art automatic message accounting equipment identifies a calling telephone station by sequentially searching through the digit leads of all telephone office station identifiers assigned to every telephone office of the switching system to locate the directory number digit signals of one calling telephone station. The searching process from one telephone office station identifier to another to identify one calling telephone station requires a large amount of the time required to complete the calling telephone station identity process.
In addition to identifying the directory numbers of telephone stations utilized for placing toll calls, many telephone switching centers are also required to identify telephone stations placing local calls. Identification of both local and toll calling telephone stations presents prior art automatic message accounting systems with a telephone station identification workload greatly in excess of the capabilities of the present toll telephone station identification systems.
Accordingly, a need exists in the art for an identification system arranged to identify a number of telephone stations currently placing calls through the telephone offices of a telephone switching center. A need also exists for a telephone station identification system arranged to identify a plurality of calling telephone stations within a specific interval of time selected to decrease the time previously required to identify a calling telephone station.